The present invention relates to a chassis employed to house electronic circuitry and, in particular, to an adjustable chassis suitable for installation in the instrument panel of a light aircraft.
Such chassis are generally defined by one or more sheet metal or drawn metal components snap-fitted or bolted together to fully enclose the electronic circuitry. Often this circuitry is contained on a rectangular `printed circuit` board of fixed dimension and, practically without exception, includes a connector at the rear thereof (i.e. for power and other signal inputs and outputs) and one or more switches, controls, or display led's or other indicators at the front thereof.
The light aircraft instrument panel presents some unusual challenges in connection with ordinary chassis designs, namely, the variability in panel thickness and trim found from one aircraft model to another. Aircraft instrument panels typically include a structural steel panel over which, sometimes, a decorative plastic trim panel is placed. Thus, the problem of variable thickness instrument panels includes, first, the uncertainty and variety of `gages` of steel employed in the underlying structural panel as well as, second, the existence (or not) of a decorative panel thereon.
As a general rule, most light aircraft include a plurality of punched, often circular, openings into which instruments of standard diameter or cross-section may be mounted. But not all equipment is amenable to these standard openings. Many electronic items intended for installation in an aircraft instrument panel rely on the drilling of plural, spaced holes through the panel--generally utilizing a drilling template--thereafter, the insertion of the electronic item into the panel from the rear. The electronic equipment being thereafter affixed to the panel by appropriate bolts, nuts, or other hardware that literally clamp the front portion of the electronic chassis to the panel.
When utilizing this common `rear mount` approach, it will be understood that the various switches and controls (to be accessible to the pilot) must extend forwardly from the printed circuit board through the aircraft panel(s)--whatever their combined thickness. Herein lies the problem to which the present invention addresses. To the extent that these controls are long enough to penetrate a combined `thick` instrument panel, the controls will be too long and extend too far through the panel in the event a single panel of comparatively thinner dimension is employed. This will result in the controls and associated knobs being positioned well in front of the panel which, at the very least, results in an aesthetically unsatisfactory finished product. And, at the other extreme, if the controls are rendered short enough to be attractive when installed through a so-called thinner panel, there will be insufficient control shaft length for the retention of knobs or for the engagement of mounting hardware when mounted to a `thicker` panel.